state taxes in Maryland and Michigan

I am filling out my son's tax return with TurboTax. He lives in Maryland.

Last year, he received a Pandemic Uninsurance Assistance (PUA) payout from when he lived in Michigan. The claim had been filed in 2020, but it took until 2024 for it to be paid. He has received a 1099-G associated with the payout.

 

My expectation is that the PUA payout would be taxable in Michigan but not in Maryland, as the income was entirely attributable to Michigan. Is that incorrect? I can find no way on the Michigan non-resident return to include the 1099-G as Michigan income, nor any way on the Maryland return to exclude it. Is the 1099-G considered Maryland income because he lived in Michigan at the time he received it, even though the claim was from when he lived in Michigan, and was paid by the state of Michigan?

 

Thanks to anyone who can provide insight.